When security affects schedulability of TSP systems: trade-offs observed by design space exploration

ARINC 653 introduces the concept of partition that allows time and space isolation in real-time avionic systems. Tasks are assigned to partitions according to various objective functions or constraints such as safety, performance, and security. Some of these objective functions may be conflicting as an improvement of one objective leads to a decrease of another. For example, improving safety by active redundancy may decrease performance. In this paper, we investigate the conflicting aspect between schedulability and security in Time and Space Partitioning (TSP) systems. Many researches have shown that enforcing the security of a system results in an overhead affecting its schedulability. We formulate a design space exploration (DSE) process with a meta-heuristic to explore solutions defined by the tasks to partitions assignment according to security requirements and timing constraints. Experiments are conducted with the Cheddar scheduling analyzer to characterize applications that are concerned by this conflicting issue and to evaluate the tradeoffs between schedulability and security.